Why did Edward I intervene in the Scottish succession crisis?

Edward I intervened in the Scottish succession crisis primarily to assert his authority as the feudal superior of the Scottish monarch, viewing the crisis as an opportunity to assimilate Scotland into his realm.1

Following the death of King Alexander III in 1286 and his granddaughter Margaret, the Maid of Norway, in 1290, the Scottish line of succession ended, leaving 13 claimants to the throne. The Scottish magnates requested Edward’s arbitration to resolve the dispute. Edward seized this opportunity, insisting that the claimants recognize his feudal suzerainty over Scotland before he would adjudicate their claims.2314

While he initially appeared to act as an impartial judge, his subsequent efforts to exert effective jurisdiction—such as taking legal appeals from Scotland and demanding military service from the newly appointed king, John de Balliol—revealed his intent to treat Scotland as a fief. This aggressive assertion of power provoked the Scottish nobility to resist, ultimately leading to the Wars of Independence.231